SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b19d0ff9944d6312c8bf98fffb0ccbd3e25d853df1a11d639aa5cc17c8e04958' 
  AND token = 'r6UjncXHRaOto0UYerumn697dAcwGn66KiRiJK1IXgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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