SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b5d365657cbb4c68abceb91c66eb30cedecdf82c1192a8c30b1bc6c2a6cba21' 
  AND token = 'F50deBw8oYVzsVzN51Fwu4uSwj41q8hkzxRLr1txQnU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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