SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '540a8c658f0778e0166bd0017551f46da8809c50f8532976051344c2281f764a' 
  AND token = 'ENEKas7lIL2cbOXsKigLiKd89goKhhwDEezBI7exA54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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