SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78c166e7afb4d57094ea80b6ea6a87601a45d26a5a4d38969d027132eb7fad2a' 
  AND token = '/8TK9nqvhuCTTuEqUOY9eNeFPcWuBlWJIHRVgdJHjXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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