SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68fec3571dbdd5f1e51edd0ad9cde42d1bcb1efa2940a28cb02ffa853d18ad12' 
  AND token = 'AYK/d0jwQ/N6/X1uPeBtgnURLKZUzsCdPAINZUR15Bc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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