SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '645a8d93c645452e1c732bf64d3b57b5d80a8e601318e45487e1db111bcb9759' 
  AND token = 'DhaiXdFmSqXy9BzksQokItlvhplyLdazGwjsvumvZ2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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