SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b71456763ff87c6db3ce39679a22df45c44ba0c31c83738f4dd0f8538091a31' 
  AND token = 'd/cDVEYAb0kWZXwMWTnPNsYO25kSIgaIRCl5795OEoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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