SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c1907c49725a602b77824f7b9475a2d99ee6413cb2b25472855fa6b007cb350' 
  AND token = 'ihPZEI/LhmpJLKJQA/oPeiCmjTw3LEPjY929s3e+2Zg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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