SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b70b16b44b682eff59761c897f9073f56eb812885258e7a06f91580b5a064f32' 
  AND token = 'rnunlgcNKMEQYvYy4XrCp6VCoM1k35HBvCw/X80JduU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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