SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a7e3162ae5b123b2353b7920e116d3a4e0376b256780fed83d26bc7ca74afe1' 
  AND token = 'RH87iQQm6shAMrTY/bfY1tCMkmJe7NZZHEGcyZ5jko0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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