SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dc8d9e2b201364da13c795681e7c47a79d8f8a50fb2c6f7393885bd82034651' 
  AND token = 'CBupf2HWt5nNCEiBVuch4qJRX24qkzB+hwpVIPO7Ft8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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