SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36d50c050ba1bc20d1a96c2c25ff7c43715b0442f1a25b32159be840b247a32a' 
  AND token = '18S7pCjzL4QbcmeFdbO852d2pzuCGBsmXca7/DUUSUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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