SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51aecc75e3efe9529fd85d3785ab9f13e2ecfb1384f6c46ca7a0c147c59f4ca9' 
  AND token = 'DPY3Gl722owzG+OLMWg+CUS58b1wrcZFNAOrlwFuApI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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