SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b46292071641b36da340769fb820942925a2116cb19e778168553d910a2896d' 
  AND token = 'B5WVi4mvOcqboGp2ta19kW7mbokCaSHRBI3NfswWPAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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