SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6193df0def44027417ee952489a4eac93c10a27e7cf43bbaa5e279f92698a387' 
  AND token = 'EZSnstgA/0Xq5PdJzUohlTDYclFNBbonZWzkUN8CQyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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