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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4f74b3f2a105b5aa2874e3ebc8ce3b146006f6e6b581ed59442cfd3d4246c42' 
  AND token = 'gcfurJ7E52+ScExDcjgDj2h+nw2zm7g5IK/pB22ZvaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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