SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f73b021ed1dceb53cbbd846ee0a2f68711adf04ceb70cd4c8ab02d908e6816fb' 
  AND token = 'QkAMpE0CaDOBtvFG7j/dR+UCJntv4LRaA0pXwLm7+Ps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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