SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '870fd1555ada279da2189878897a9990d27ecf8a837a1548ac216cfcba541606' 
  AND token = 'ADDDSqZW0frlD3SEJ8uAF/pJpjsZEVidfmeY46ge5Ig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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