SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e5ce49202fad7a3194acf9137a40b4ac98de288680b7eac9af560e29357aec3' 
  AND token = 'kgB1DgwMb3/kPEiJU6AZjYnOAsgmqALbCm4Kg/L+d70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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