SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2d39126c53f951a49523f9ff7f3edd2a89fc84d83eef479a042376ae7a08239' 
  AND token = 'eMje11MSJEIH7Q8r3A22sM9vW48Sip72r39Gq7mjeBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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