SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6ebc56f2bb9eaa1353326c8226041523869aa77169c0bcfdd827e6ad434e116' 
  AND token = 'eQUjdSbLnyruzbJnKgYPNJV5/JWwC0iVl7UfT2ST+qE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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