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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af66d78cdc4300cb284ea9717c94997c3aac6b66d16dc18b268000bcbc74a1a0' 
  AND token = 'DCw4mpZqIiU3RgQLtEU9iY/eO/Ui1GDriWuQvJ5/MGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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