SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b310866db4fd3e30db5026e058d2ca88d4d984eae519e0694f37688d45c40c98' 
  AND token = 'LTErTSAPVKLmZXf9SQgJRKvh+PYASxYqgX3jmDNJ0Z0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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