SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b94d41aebd1f16811261acd14e9d1a825925abdaea5e6f66e2cf442c50a319dc' 
  AND token = 'XbUrm7fctGyMZ2Agn49EIZ8vHf6Op57f0sqiJvJoYMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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