SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '32e253145397cf4ffd1a20ca5356fa6c666b0db8961b1ef267db3a51dfd00ea8' 
  AND token = 'PUWhFcq9BEe6fOsYvkfVFCPr4/JjBbcLhVXb4UgMzZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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