SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35658116fd1ae921fcabaff4052ed8d297d14fc402eadab3a61ebc4c3520a276' 
  AND token = 'mX5vxT61TRdTd/mShLnqh8Zn8MlyFRdjOrxFoohq+yk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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