SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16aa3e05dad609e4ca0acbc8e9e65f6986784bbfe2a0350d857687275be609a7' 
  AND token = '7DDCKvy8pl+99uDQ7VGnnq976akhkiNIOSf54eQwNPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}