SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b606d2b452995f441263880b5371ff86484f3cc044c3475c2ae17935ddcdf6a' 
  AND token = 'hLcHtx0iDu0hRMsCAYnzb+X2ccjRHDUoH4vdANFwz7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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