SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38cbd75187f3985f6dbf1298e4fe027e9194d65522fd9c4bdb43196bdea70fb4' 
  AND token = 'fcu/HINBVQ9SDYtDtn9DKMb5xQrd+5partNqUqmP6Vc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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