SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '186e544a92198ef4bab3f52bc324882e628e9560f68346d4e75ba62c1f831fae' 
  AND token = '/NLk3ixXw65MxYytsAkm2hUVgQN27aLuVXTzgjKo0hc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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