SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79c5c44319142da18a82a14ad639550e74d36b2e158755813559f8a92fe12b76' 
  AND token = '3HC1yddBHBRlgvF6/2kXfxFGqUqjK6wJBIkEdsUJuCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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