SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38bb48a8a409ec1db015382655ca89a63e54321e605b33ea59db90c098ff474a' 
  AND token = 'EQ7YYwlDTMo9QxTkmqYTdmTzfoGyCnLORyASujy4xjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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