SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '054c829954a1d98c6f57176bc79c33385e0f35252ebf05dcadd99ad2896f62b2' 
  AND token = 'KPRvlzFjWDeW8qaEj3AdN2LnyXOe52eORDVPC7rZtL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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