SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8a3c6384c8d5f14ae7f7c4af54f374c92f7f0d1eb6cc37b83b2fd4f9a4da242' 
  AND token = 'nPTIU3PuKSF4dCG+AziPB6OKV9zGFnKqXJ9E6hys4Qw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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