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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd253abed13d3aa989183ccb2c4a0a81cddf81ae32f3af7b4d7e78012d6ef3438' 
  AND token = 'a+L91QiWco4VZ4Z1Kv3MvFdeMc9Po32BgCfzOcyR7P4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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