SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '198b9505f02f38c77d4150a1e921b1632ea6012ce202a714ec8a125a793d2d58' 
  AND token = 'sUvqWma7F4C4RUNkr6chM5bhIHgRCNAY+j5/iYgdpz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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