SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1986ec3a61b8e55378d0c9b82e3be8dd34e51c30303e851796bd4546d4397f7' 
  AND token = 'Z9kVah+DHgRq2nrlABvJSOB2HJzh1vcgznO/XVa8wRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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