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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a33f4fd81f66eaf14a1b7345c577f6e9b8e5bbd69cf5ec33e6f36dacadcafb06' 
  AND token = 'kr51IOWacq9pQioa5lQ0z4qKlxZXVqCSogN0ueMDt94=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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