SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '555dc20aeaf646ce5eca5f98459da05d08b7257f8e54deb65d4cde0f88684823' 
  AND token = 'z4SP+eh/9OWL5RE2ARrdEqzSidqMM4bCM82e8wvtdbE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}