SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e467dafb3fd2ed70d704314cdc511920bab44d2cbc21371436b3a7f30c9cff5' 
  AND token = 'loLs8u3fg9UOXh/AeifbYmt2PKHfmLxcjlgP4NqFN5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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