SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e9fb7757876fa92a660fc6227a90806e532830c452447c8ae5b741b0f021486' 
  AND token = 'JQLRkHPlcztM8gOr4OiEnCGRfgDr9fZR6PWfD6YjRw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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