SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af1e2a1c4c1a3c4dfa86aff3e580a83398193db135ef52451b488e542b68dc34' 
  AND token = '8d/kwGHNHQvQb2XWFQO5rkKARgskd6UI9TCs2FIggFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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