SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e75ccd3f0192fe6e4c7d72de8c03a7d83ba3131907ff52d724bcd6eff4d81c9f' 
  AND token = 'RCmBmNSzV5HU+FCLQuByPQmSVwYqJG36IXnj+B0Ht1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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