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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6e4311df382818351a80c1f73bd92eec4b9607dd30de1f09eb06de6bcb36a21' 
  AND token = 'ewHnG0K/ZzQ0JVF5TJx59ETGooS/1txzHHt9M3YALr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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