SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9621ded25cf564325e172df9e0b6f892becfcc30456c0bf5e3caaeae674d092c' 
  AND token = 'w6+jXTXC7FZbNZ3BTMkpY331mKFgVVvKNHZRXGUGEUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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