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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c79f788d65ffecc257c5c493833aa3edc7e9b7421600c01392e2a1eb2ae20f5' 
  AND token = '74yWe1z+qpXFz8c8AiGjdIGWKSaVtIe+B5rFZDP0dKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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