SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd55b712283f52f414e759ecd1d1a0e62dd1a11393d4ac52e928689bd38a9ba44' 
  AND token = 'xyzMc5QtONPIM/yrllHFS8qEs73sl9dvxTqhLavnA5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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