SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '789e58998eaa086693e0d1ee2815ebdfae70453347097d8a306bf3782da30977' 
  AND token = 'hS5JNp2ao9HfEqmZlmmcSb6OmPt4c3qvxRdREodLqdg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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