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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c7e56c841de09b7d79ed3244e10fa4f3b32c5f7de83d0c779439749f9fe87e3c' 
  AND token = 'QFnjOENo16YonUmiYe6XwWpdRSUGHV7AgZeEunyqFDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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