SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4c9051a203ba06c1cdcb6148cf4918a03b89fab59986ef1fa62d3f0458a18ba' 
  AND token = 'i/YLlM9rlwaDQfjdWvEX1AgwojrZm8JbMOufaqbHjq0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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