SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37c5b78d17672641615f09447d9cd436d708664df0b3289a52642e50128e1098' 
  AND token = 'PCCSr293+kXniGvYsd1LbBVLdZqNaasCho338wZXweo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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