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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3ff604d2e722578fec494476d005dd7e6157c0986fc6e8f7c59f2d5d6e6d43f6' 
  AND token = 'VQ5jGtAxTYFeRivl9a+HR+PVaQzVLuI6LyVNQDVCn6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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