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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb4006ac5d6978e9a2a21cdbbeb0d2ee643fdb898821e8f7257bc0a4b92f5fd7' 
  AND token = 'D7cc6eb1+Qa7P12ovn7E02G0KPIlQjkfAAx0NEUQAJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}