SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8757fb8cd5140565c46308672df32662df7bf630c51e01839a76cf956109ab59' 
  AND token = '/CJL9KRF9vNSQZz46h+sLZRz3PzeHjoBK7NNfPfDPZE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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