SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1893f2f3023dc63f9348b03605c6ce02d4da2f2bfd736071a61893ac5ea67ad' 
  AND token = '1JzdKpBeYxffAVd3K2uRCuWnGrBYE1kR/FGeLWqwmco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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