SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5c70d1d31a8d62825f604d04ee21116b68a14e286f55a135f561cb7d5e88fb0' 
  AND token = '9kQFAPmQc5wp1HqmGXy9opvSVkt8Be0KbrZIcsJw/BE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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