SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ead81f292abb92b49fe89e0b631b65830c6e6027d2793fd60037317acb4365c' 
  AND token = 'lOQh38udEMdVffOL84Wp81z2yZ6McZxi+1nkaI2wGnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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