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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e4e6e20daed1bd73760819b74c19e7ffb5ef5259a544e9febb8ffda5a1854d45' 
  AND token = 'QUMmi6FxAKCBPcIh7hIBuK4UbCD5IxjAj1IfpVZmazs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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