SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b3cbb4bad2dec3b81f230c21daa96246dffe30a6d07015bc9e8ba8600210035' 
  AND token = 'NBXk43SwjQfNsFThK48p+10Lsl2hrBf6wc/rop/U4J8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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