SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1cceabb50c628765b80ef69830074f4c77f4b1aab6a3cadca821635ba2bcced' 
  AND token = 'Tjhw3jzU1R5DDGruWR1FhmE5uttvGYGUgcmEbydqH/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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