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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9c875f749308bff653385a34dfe4406b74193accf336c72d979f405649c66ee' 
  AND token = 'Vs37uyh7Sn3QTsPKoHxbToHPa4dIFSVneNyRYhix6EA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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