SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55eecccc2f84fc5492b0b6fdc02a816e15414da584c1655c601a24834e985a16' 
  AND token = 'A0t5JYRVQt0D6bDo1LLL6o+cpRkI8xZsH5zdkH/Bv+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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