SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5289fc75b3d4710458e658adffdc327a89a403b33c1e8d3b26cceb3956a93f2' 
  AND token = 'C1ks2zPtshgkPkyEPslUgGVC8knr4FJtVSjf//Fqdvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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