SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '942d38282763094acf4db465a7836f84ab64acff5af78f4feb76794ec29ed2f6' 
  AND token = 'BoyPdRQ8WTXBr3LRDfcsS9ssFAmBfeZyPKPbGz9RS10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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