SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e8dd3fb246bb9bfa3679028413269ba62823d687a486586197fe5135eddf109' 
  AND token = 'ZcDiFfNFrtRU6shRV/nXz4yQhGGjSLOzB7pqZiibQgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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