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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '347b778c3abc8a24b9a3a15d5ba57d195b859f47870ea3399a9c311c01b71cde' 
  AND token = '0LZVKpXRHSlRWKCov6sMmD320Gn93nhnWdxHUCMsvdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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