SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '153738ea350fda3227b2577f571e0a49e7af3b65714710fface9e7c8034c47a7' 
  AND token = 'SrRhy1t1Sm6Admez4DD3t5y7lqGPpecqtiabMclilFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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