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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '273c9122edd47ed5122c45ec5756476185e9b2f1e225509e79baef57c7208b5b' 
  AND token = 'WgXMs3AITzB08abhiabSshDeMce8sMAThU7yIYVfi30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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