SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e15c4651565eb1470d9dbaddce2f59cc93d2d5df165f015df8ac0d96a9eff51d' 
  AND token = 'O8vOU06vIVpA1LO3dm2WR2QdMzeAMXuT5RPdWdCdWIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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