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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b70e678891d27458e5052c944adf0c052d1c8e818f1f45f93ec5cf4b90861301' 
  AND token = 'EJrjvhnkHRQ7Av0vcU0yPj9Ke+h9SSRI2hGc+y2Wv34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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