SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fb825e3d2a46319c8a9f0a39aba0326421afb941e2028ed688056793be0a106' 
  AND token = 'ByjYPN5n43EVbvANTtQ7s0B3BBPTawdYSxoDD/GtHXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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