SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97cc502b18b573f8a1e07042ee082388d09595b3f19352bf586117898b6ac641' 
  AND token = '8WQnUWQzR+/0FvQKu1Qi+NCd+gpBpqjPTvkhXiVHF5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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