SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39f18f4ec350f494fe5957803e150818169283cbc631648d575e27d365d01987' 
  AND token = 'B2u2gbVkzmYv5uvxbRJzzQoGl/gjk5HX32ZLpd8oK3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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