SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51369cf1116088d87a693868eb43cb93987676bf5490f8582fceb4409f1d6245' 
  AND token = 'fs/q2V05+mDXsqRtB0Tv2U/9/Zsj4O1YcY5WBWzNt9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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