SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '837aa1b2add180708a77cbfb8915977607230b343fe75686c06a1b83caddcc53' 
  AND token = 'CkFDCdmMqlqjL9a1BA9AvDPKEu2kwdIcxmvmzHEwvWA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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