SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0747671c1b24beeff023144e3a30b96caadaa53569a9eca606f556a245e59d42' 
  AND token = 'mqim09eKzDv5kdY4nl6sD6V0lCPji+KR28u6g60D3Uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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