SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c666e656931e4a237fbdfb95d8a53863a4f9ed89ae4afd8b1f9606eea8ed5dc3' 
  AND token = 'iCOmNH1gMK1MUhcJ62Nb/UOPhL8j+HVdlXObWAL+86I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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