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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6751a967b4bd899e20e44eb8ab5a2e938b9d10354a8cfb29aeb2ef0aebb1291d' 
  AND token = 'q54vJxugO+aM8V3g/zac0zpdMeGWhnv3ZbZEX+gyLxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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