SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '788be31b6d95d46206aebc9db4a43baca764b4430ebb9375562f5985b148e367' 
  AND token = 'OsGssjGkfskvIhLimBiUx3xWduS7j7VZI4XNEDyPea0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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