SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0250cc45914efa7d6d144bbc02c5f1f6df89486b162f98bcfeabc3bd5394fa1' 
  AND token = 'tx5kyjyvwQBn9x3y1BtzqBGN/ZbOdiJ0LxH7XCYoFvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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