SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4664e3bf84814134a97431a9c4061031d997aeb2c721e1421b4e728b16f2c4b7' 
  AND token = '2a1PaBoaNWSdp4Sgmc4BQYVId1197FNcHd8+bFbzIeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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