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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8fa0578f8fbd855b7a8e6acf5b2ac6984b54e0fd533c19912a10fdd15c82cf8c' 
  AND token = 'QF9JYI0mKJcyV6KaSuL2q0WjCKiWe9D33FxBwGTTNX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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