SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e060e634833bb3827888cf41216cb8953ff95c466d94e3330b70eee363e8cc4' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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