SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b70355fe653eb8f0dd7417b5593420924228c965db760a014ade285e13020ef' 
  AND token = 'llHdOGZZG/BlW/QmI8VBmNGdB2BIVVVSf8gjcm2RR1E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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