SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5d8336eb688821ea910877b45731d395878242c838602b7d8b0cba821434f48e' 
  AND token = 'qIyGwpx0VyAFSzqdE/urPotM+vbQ+MohCDsNPj9KS2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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