SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d5eff29dd5fe22e27e98bde6f9ff6c8e81c5f88f030a53f1bb8313adca98623' 
  AND token = 'kk/8Kvd+CQdcpVtqY3z3i+dhdq9stMIk+ql7QZJegOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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