SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad3d22c6781d001119aeca7d9fb63143042d93566a5e1b96e8f0c9c7b7da665c' 
  AND token = 'VksUOeVvv+nxDiQ6mhaondCZxR4Dk4PhPq7VOtT1BEw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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