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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '154b90dcb6df12bde036ac5888cb0b7b2ac22140620c2d0e5e31a868b7c2ad8a' 
  AND token = 'YZ7DZul4YRfrt0CmzAVV1QVMVlSiY2PrzuV+m8nh+gw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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