SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd583f3a035fe378d817fed3ab6f653b580af2c4b34b4467c7c8f9fb3c27bc51c' 
  AND token = 'enmxCkKnl+4PBazaLDqgv8uFuG1DK2jfZeCp8GevrtQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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