SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac233312cd4990c8d6a792db684bb9c66c33b4bfaafd0d9323d24530f257bb88' 
  AND token = 'hK5gg+nHBwlxTwaC/DfSRTaPn95tM5norHobBLXsM50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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