SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adc120903cbaa109e03e0038018c4b53d90380c6615da146ea7db219f86c8534' 
  AND token = 'CPB5HeUu+6pnbs8wsLJbDfglDi/8OvVZeAMOwP0qk8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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