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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1696d1812eb7cc6420b21425dffe1abab806e468952a786af0ede9d4947aad8f' 
  AND token = 'nQP+SDiRJu7ZIEarrT2dAeES7mhNI6yHejJxRWStun4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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