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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb50014ec3e64ecf0b15b72bf2e6f825a98fe0f9421a775a6db9542d96f5dcfe' 
  AND token = 'RLAL+GIlnDmzWOfgl/h2ZANl2wYuib4BWsc1pqLM9Rc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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